EC-COUNCIL 212-81 Online Practice Questions and Exam Preparation

EC-COUNCIL 212-81 Online Questions & Answers

• Question 201:

  Basic information theory is the basis for modern symmetric ciphers. Understanding the terminology of information theory is, therefore, important. If a single change of a single bit in the plaintext causes changes in all the bits of the resulting ciphertext, what is this called?

  A. Complete diffusion
  B. Complete scrambling
  C. Complete confusion
  D. Complete avalanche
  D. Complete avalanche

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  Explanation

• Question 202:

  As a network administrator, you have implemented WPA2 encryption in your corporate wireless network. The WPA2's ________ integrity check mechanism provides security against a replay attack.

  A. CBC-MAC
  B. CRC-MAC
  C. CRC-32
  D. CBC-32
  A. CBC-MAC

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  Explanation

  CBC-MAC https://en.wikipedia.org/wiki/CBC-MAC A cipher block chaining message authentication code (CBC-MAC) is a technique for constructing a message authentication code from a block cipher. The message is encrypted with some block cipher algorithm in CBC mode to create a chain of blocks such that each block depends on the proper encryption of the previous block. This interdependence ensures that a change to any of the plaintext bits will cause the final encrypted block to change in a way that cannot be predicted or counteracted without knowing the key to the block cipher. Using in WPA2 for integrity check and provides security against a replay attack.

• Question 203:

  Protocol suite provides a method of setting up a secure channel for protected data exchange between two devices.

  A. CLR
  B. OCSP
  C. TLS
  D. IPSec
  D. IPSec

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  Explanation

  IPSec https://en.wikipedia.org/wiki/IPsec Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts the packets of data to provide secure encrypted communication between two computers over an Internet Protocol network. It is used in virtual private networks (VPNs).

• Question 204:

  A _________ is a digital representation of information that identifies you as a relevant entity by a trusted third party.

  A. Digital Signature
  B. Hash
  C. Ownership stamp
  D. Digest
  A. Digital Signature

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  Explanation

  Digital Signature https://en.wikipedia.org/wiki/Digital_signature A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature, where the prerequisites are satisfied, gives a recipient very strong reason to believe that the message was created by a known sender (authentication), and that the message was not altered in transit (integrity).

• Question 205:

  What advantage do symmetric algorithms have over asymmetric algorithms

  A. It is easier to implement them in software
  B. They are more secure
  C. They are faster
  D. It is easier to exchange keys
  C. They are faster

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  Explanation

  They are faster

  Symmetric key encryption is much faster than asymmetric key encryption, because both the sender and the recipient of a message to use the same secret key.

• Question 206:

  Changes to one character in the plain text affect multiple characters in the cipher text, unlike in historical algorithms where each plain text character only affect one cipher text character.

  A. Substitution
  B. Avalanche
  C. Confusion
  D. Diffusion
  D. Diffusion

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  Explanation

  Diffusion https://en.wikipedia.org/wiki/Confusion_and_diffusion Diffusion means that if we change a single bit of the plaintext, then (statistically) half of the bits in the ciphertext should change, and similarly, if we change one bit of the ciphertext, then approximately one half of the plaintext bits should change.[2] Since a bit can have only two states, when they are all re-evaluated and changed from one seemingly random position to another, half of the bits will have changed state. The idea of diffusion is to hide the relationship between the ciphertext and the plain text. This will make it hard for an attacker who tries to find out the plain text and it increases the redundancy of plain text by spreading it across the rows and columns; it is achieved through transposition of algorithm and it is used by block ciphers only.